State energy regulators today announced a fine of $24.8 million against utilities for their response to Tropical Storm Irene and the October 2011 snowstorm.

The penalties include $4 million to be paid by NStar, which delivers electricity on Cape Cod and Martha's Vineyard, and $18.7 million to be paid by National Grid, which delivers power on Nantucket.

“As the number of serious weather events has risen dramatically in Massachusetts, it's crucial for ratepayers to have electric service that is both safe and reliable,” Massachusetts Executive Office of Energy and Environmental Affairs Secretary Richard K. Sullivan Jr. said in a statement about the fines.

NStar officials said they intend to appeal the fines and “strongly disagree” with the DPU's findings.

“The amount of devastation our system sustained last fall cannot be understated – with an estimated 80 percent of our overheard circuits damaged after Irene alone,” NStar President Werner Schweiger said in a statement released by the company. “We were essentially rebuilding the electric system as we restored power, and the penalties assessed today are simply not in line with the realities of getting the job done.”

The DPU found that NStar performed reasonably in many aspects before and after the storms but that the company took far too long to respond to priority calls from public safety officials about downed wires and did a poor job of communicating with its customers, according to the DPU press release.

The Attorney General had called for $10 million in fines against NStar for its response to the storms.

Irene, though less destructive than initially predicted when it struck in August 2011, knocked out power for more than 500,000 customers in NStar's territory, which includes Cape Cod. Although almost half of those who lost power had their electricity restored within an hour, some customers on the Cape did not get their power back for more than six days after the storm.

Outages related to the Oct. 29, 2011, storm affected about 19,000 customers on the Cape. All of the Cape power outages related to the October storm were restored within about three days, according to NStar officials.

The utilities - including Western Massachusetts Electric Company - are required to submit plans to pay the penalties within 30 days, according to the DPU.